1. Field of the Invention
The present invention relates to an external device to be connected to a camera upon use, to an electronic flash device, and to a camera.
2. Description of Related Art
The following type of wireless light increasing system is known. With this system, an auxiliary electronic flash device starts its own light emission operation upon detection of the light emission of a master electronic flash device that is connected to a camera. (Refer to Japanese Laid-Open Patent Publication H06-267682).